Recently, a utility vehicle (UTV) is widely used in wide fields, such as distribution, construction, leisure, and agricultural use. In particular, a utility vehicle has a structure advantageous for steep path driving, and thus the utility vehicle is chiefly used as delivery means for carrying soil or the crops in construction sites or agricultural site or for carrying tools necessary for various tasks.
An electrically-driven type utility vehicle which can implement an eco-friendly vehicle because it never generates exhaust gas and has very low noise, unlike in the prior art in which a mechanical engine is mounted, is recently searched and developed. The electrically-driven type basically includes a motor for generating driving power, a battery that is an energy source, various control parts for controlling the motor and the battery, and other peripheral parts.
Driving speed of such an electric vehicle is changed by control of the output of the motor that is varied in proportion to the manipulation displacement of an acceleration pedal, and a motor is passively rotated by kinetic energy of the vehicle that is being driven when a foot is taken off from the acceleration pedal for braking while driving. Here, counter electromotive force generated when the motor is rotated by the kinetic energy of the vehicle and stored as available energy is called regeneration, and resistance generated in such a case and used as braking force is called regenerative brake.
If resistance generated in a regeneration process as described above is used as braking force, a braking force deviation is inevitably generated between driving wheels (front wheels in the case of front wheels driving vehicle and rear wheels in the case of rear wheels driving vehicle) and follower wheels in a vehicle braking process. That is, when braking the vehicle, mechanical braking force and regeneration braking force are simultaneously applied to the driving wheels directly connected to the motor, whereas only mechanical braking force is applied to the follower wheels.
When such a braking force deviation is generated in the wheel, overall braking stability and riding comfort, such as that rattling is generated in the vehicle during braking or eccentric braking in which the vehicle leans to one side, are reduced. In order to overcome such a braking force deviation, different control systems are constructed in the driving wheels and the follower wheels in order to compensate for a difference in the braking force. If the control systems are applied, however, there are problems in that a braking device construction becomes too complicated and costs are increased.